Reversible rotary motor



April 20, 1937. A. AMTSBERG REVERSIBLE ROTARY MOTOR Filed Aug. 13, 1935 5 Sheets-Sheet 1 D. a M W 0K ma F/ .3 1 am 0/ E o@ E Z ATTORNEY April 2o, 1937.

| A. AM'rsBEG REVERSIBLE ROTARY MOTOR yFiled Aug. 13, '1935 3 Sheets-Sheet 2y ATTORNEY April 20, 1937- l.. A. AMTSBERG 2,077,733

REVERSIBLE RTARY MOTOR Filed Aug. 13, 1955 3 Sheets-Sheet 3l l l l E 5*!'4061 E 4,222 4,14 40a F0 WAED l E- I \x\ w 39a 39a 29 /3 'ge-72 7a /4 Y) g? /Bcz M0@ A Y a j v E Q 402 425 44 40h' INVENTOR .6 0 l isn-1e 'A 444755526. 44g 4g' WY 4 M 45 ATTORNEY Patented y Apr. 20, 1937 UNITED STATES PATENT OFFICE REVERSIBLE ROTARY MOTOR Lester A. Amtsberg, Cleveland, Ohio, assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application August 13, 1935, Serial No. 35,920

3 Claims.

This invention relates to rotary motors operated by an expansible fluid, such as air, steam, or gas, and more particularly to reversible rotary motors of the movable blade type in which the blades are Lcarried by a rotor eccentrically mounted in a cylinder.

The usual types of reversible rotary motors are inherently much less eiiicient than corresponding non-reversible machines, the air consumption for the same amount of power being approximately fty per cent greater. This is particularly true of machines. in which the ports of the cylinder are so arranged that the inlet port for one direction of rotation is convertible into an outlet port for the other direction and vice versa.

' ing space between the rotor and cylinder wall.

Maximum emciency for one direction of rotation requires that the exhaust port be relatively close to the center of the working chamber, but Athis condition is not attainable in conventional motors because any relocation of the exhaust port results in a corresponding change. in position of crease in air consumption, reduction in'power and loss of eiciency.

An object of the invention is to increase the eiiiciency and power and to reduce the air consumpticn of a reversible rotary motor, whereby to obtain the advantages of a one-way motor in a reversible machine. A more specific object is to eliminate,'as far as possible, loss of power due to compression without shortening the power stroke of the piston.

In accordance with this invention, a rotor or the type having blades carried thereby.7 is eccentrically mounted in a cylinder to provide a working chamber of crescent shape, inlet ports are symmetrically arranged on opposite sides of the working chamber, auxiliary exhaust or relief ports are arranged intermediate the inlet ports and means are provided for closing the relief port or ports on the power side of the chamber.

In the preferred embodiment of the invention, the relief ports are controlled by a pair of plate valves normally held in closed position by springs. The relief valves are so arranged that pressure in the working chamber of the cylinder forces the valve on the exhaust side open and the impingment of exhaust air through the relief ports against the face of the valve holds it in open position.

Other objects and features will appear more clearly from the following description taken in connection witlrthe accompanying drawings and appended claims:

In order to illustrate the invention, one concrete embodiment thereof is shown in the accompanying drawings in which:

Fig. l is a longitudinal sectional View of a reversible rotary motor with the throttle valve shown in forward position, the section being taken approximately along the broken line I-I indicated in Fig.l 4;

Fig. 2 is a sectional View looking in the direction of the arrows 2-2 in Fig. 1;

Fig. 3 is a sectional view looking in the direction of the arrows 3--3 in Fig. 1;

Fig. 4 is a section as shown by the arrows 4--4 in Fig. l, the rotor being omitted;

Fig. 5 is a sectional view corresponding to Fig. 3 but with the throttle valve adjusted to neutral position;

Fig. 6 is a section corresponding to Figs. 3 and 5 but with the throttlevalve'in reverse position;

Fig. 7 is a fragmentary sectional view corresponding to Fig. 4 but with the throttle valve in neutral position;

Fig. 8 is a longitudinal section through the line 8-8 in Fig. 1 looking downwardly;

Fig. 9 is'a section along the line 9 9 in Fig. 8;

'Fig 10 is a longitudinal section of the cylinder,

taken in the same plane as Fig. 8 and looking downwardly; and

Fig. 1l is a fragmentary sectional view similar to Fig. 5l but on a larger scale.

The embodiment of the invention chosen for the purpose of illustration comprises a motor having a casing I2 and cylinder heads I3 and I4, which are maintained in assembled relation by suitable securingl means comprising studs I5.

with cylinder 24.

Heads I3 and I4 provide bearings I3a and I4a, respectively, for the shaft ends Ilia, I6b of rotor IB. Shaft end I6b projects beyond head I4 and bearing I4a to provide a power take-oil? IBc. In the upper part of casing I2, a control or throttle valve I8 is supported for limited rotary movement with its stem I8a projecting through a stuffing box I9 of any suitable or desired type on cylinder head I3, an operating handle lill)y being secured to the outer end of the stem. Stops I8c and I8d (Fig. 2) on valve I8 are arranged to engage a fixed stop 20 (Figs. 1 and 2) on head I3 to limit the movement of valve I8. A fluid pressure supply pipe 2l is mounted on cylinder head I3 and connects with one end of the chamber in which valve I8 is mounted, while an exhaust pipe 22, secured to cylinder head I4, leads from the opposite end. A partition I8e across valve I8 separates the live pressure fluid from the exhaust.

Rotor I6 is eccentrically mounted within a rotor chamber provided by a cylinder 24 secured to casing I2. A crescent-shaped working chamber WC is thus formed between the rotor and cylinder. Rotor I6 has radial slots 25 in which are slidably supported vanes or blades 26. Fluid pressure is utilized to hold the blades in contact To this end the motor is so arranged that pressure uid is first 'admitted directly beneath blades 26 and is then conducted into the working chamber.

As shown in Figs. 1 and 8, the slots 25 are preferably deeper at the central portion than at the ends of the rotor, and the blades 26 are of corresponding shape. At the ends of vthe rotor, the inner edges of the slots 25 are adapted to register in succession with arcuate grooves or ports 21a (or 2lb depending on the direction of rotation), which are adapted to deliver live motive uid to the slots. These ports for supplying the rotor slots with live air are provided in the end plates 29 and 30 for the cylinder. By comparing Figs. 3 and 4, it will be observed that each blade registers at its inner edge with the Iluid supply port 21a or 2lb for a considerable part of its travel and accordingly will be forced outwardly against the cylinder wall 24 during this interval to provide a tight seal at the outer edge of the blade.

The manually controlled throttle mechanism for supplying live air to the arcuate supply ports 21a and 2lb in the end plates will now be described. Figs. 1, 2, 3, 4 and 8 show control valve I8 `in forward position. Live air enters the motor through supply pipe 2I, passes through ports 3l to the inlet side of control valve I8, through valve port I8f, (see Figs. 1 and 4) and then through a series of passages in the motor housing and end plates which leadto the arcuate port 21a. A similar series of passages is adapted to convey live air from the port IS7' in the valve to the supplyports 2lb when the throttle valve I8 is turned to reversing position. Referring particularly to Figs. 1, 4 and 9, each of these series of passages comprises a port 33u. (or 33h), a horizontal duct 34a (or 34h), and vertical slots 35a (or 35h) in motor casing` I2 which register with slots 36a (or 36h) in the end plates, terminating at the arcuate supply ports 21a or 2lb.

The series of passages just described serve also to supply live air to the working chamber for driving the rotor. Referring to Figs. 8 and 9, live air delivered to the arcuate groove 21a is adapted to pass out of a port 38a provided in each of the end plates 29 and 30, said port being at the lower end of the groove and communicating with a radial slot 39a through which the air passes out of the end plate. The motor casing I2 has an angular passageway 40a arranged to receive live air from the radial slot 39a and deliver the same to a large chamber 42a positioned between the cylinder 24 and the peripheral wall of casing I2. symmetrically arranged on the opposite side of the motor housing is a corresponding chamber 42h adapted to be supplied with live air through ports 38h and radial slots 39D in the end plates, and angular passageways b in the motor casing when the throttle valve I8 is adjusted to the reverse position.

Chambers 42a and 42b are kept in constant communication with the respective ends of the Working chamber WC by means of slots 44 in the cylinder. When the throttle valvel8 is turned to the forward position, it opens chamber 42o to exhaust, through valve port I8h and exhaust pipe 22, and closes the upper end of chamber 42a, as seen in Fig. 3. Chamber 42a thereby becomes an accumulator for delivering fluid under relatively constant pressure to the inlet side of the working chamber WC. In the reverse position of the valve, chamber 42h becomes the accumulator or live air chamber while chamber 42a is open to exhaust through valve port Ig.

As will be understood by those skilled in the art, live air admitted through the slots 44 in the cylinder24, on the Dright-hand side of Fig. 3 acts against the blade immediately below the slots to force the blade and consequently the rotor in a clockwise direction. After the rotor has moved so that the succeeding blade cuts off the supply of live air through the slots in the cylinder, the air in the p'ocket E, between the two blades referred to, expands due to the gradually increasing width of the working chamber WC at this phase. The expansion of air in the pocket E, of course, transforms the potential energy of the compressed air into kinetic energy in driving the rotor. As the rotor continues revolving, the size of the pocket between the blades reaches a maximum (see pocket M in Fig. 5) and then diminishes, as in the case of the pocket positioned at C in Fig. 3. If no escape were provided for the air in pocket C, the contraction in the size of this pocket would necessitate compression of air therein at the expense of the kinetic energy received from the rotor, and the rotor would expend power in acting as a pump.

In accordance with this invention, loss of power due to compression on the exhaust side of the working chamber WC may be reduced or eliminated by exhausting the air from a pocket defined by two adjacent blades at approximately the time that the pocket has reached its maximum size and begins contracting. Although this result might be accomplished in a nonreversible machine by the expedient of increasing the length of the slots 44 on the exhaust side, this expedient could not be used advantageously in a reversible machine because in the reverse operation there would be a corresponding reduction in the space in which the air is permitted to expand in the pocket on the power side of the working chamber.

The present invention contemplates the use of auxiliary exhaust means for one side of the working chamber. which reduces or eliminates compression by the rotor, but which becomes ineffective when the direction of rotation is reversed, in order not to interfere with expansion of air on the power side. As illustrated in the drawings, the auxiliary exhaust means comprises two sets of ports 4Gb in response to pressure transmitted relief ports 46a and 46h in the cylinder 24,',one set being on each side of the center of the crescent-shaped working chamber WC. As seen in Fig. 5, the ports are so arranged that they are uncovered by a blade 26 at approximately the time that the pocket M in back of the blade has attained its maximum width. Associated with each set of relief ports is a plate valve 41 adapted to t the outside wall of the cylinder and cover each port in the set. An expansion spring 48, guided by a stud 49 screwed in the casing I2, engages the outer face of the valve near one end thereof, and

normally holds the valve in closed position. Guide pins'50 fixed to the casing cooperate with holes 5| in the valve 41 to prevent undue displacement of the valve. The assembly comprising the valve, pins and spring is situated in the accumulator 'chamber 42a (or 42h) in order that live air may act on the outer face of the valve to supplement the spring pressure and to oppose the pressure transmitted to the inner face through the ports 46a or 4Gb. The combined force of the live 4air and spring pressures is suflicient to'hold the valve closed on the power side of the working chamber WC. On the exhaust side, however, pressure inside the cylinder 24 is sufficient to force the valve open, the valve being rocked about the end adjacent to the spring. rihe stream of air, exhausting through the auxiliary relief ports 46a or 4Gb, impinges against the inside face of the valve 41 to hold it in open position.

When the motor is not running, both of the relief valves 41 are held in closed position by the springs 48 as shown in Figs. 5 and 11. When thev throttle valve is adjusted to the forward position, the valve covering ports 46a remains closed while the other relief valve opens the auxiliary exhaust therethrough and remains open as long as the motor is running forwardly. A corresponding action takes place when the motor is driven in the reverse direction.

The diameter or circumferential length of 'the relief ports 46a and 4Gb should be smaller than the width of the blades 2B in order to prevent motive fluid from by-passing around the outer edge of a blade on the power side of the working chamber WC.

From the above description, it will be seen that the relief ports v46a and 4Gb are arranged to prevent compression on the exhaust side of the working chamber WC without interfering with the pressure side or'the operation of the machine in. the reverse direction.

Briefly summarizing the operation ofthe preferred embodiment of the invention, let it be assumed that inlet pipe 2| vis connected to livelair, and exhaust pipe 22 to atmosphere, and the operator turns the throttle valve I8 from neutral to forward position as indicated in Fig. 2. Referring now particularly to Figs. 1 and 9, live air from pipe 2| passes through vthrottle valve ports 3| and Isf, motor casing passages 33a, 34a and 35a, and then through end plate slots 36a which communicate with the arcuateports 21a in end plates 29 and 30. From the arcuate ports, the compressed air follows two paths, one of which comprises the ports and passages 38a, 39a and V40a leading to the accumulator chamber 42a. Before pressure has built up to its normal value in the accumulator chamber, pressure iiuid from the arcuate-ports 21a follows the other path above mentioned which extends through rotor slots 25 along the inner chamber 42a is closed at its upper end while the corresponding chamber 42h on the other side of the cylinder is open to exhaust through valve port |8h and exhaust pipe 22. Pressure chamber 42a and exhaust chamber 42h communicate. by

means of slots 44 in the cylinder, with the respective ends of the crescent-shaped working chamber WC.

The difference in pressures at the ends of the working chamber WC causes rotation of the rotor, with the consequent variation in the size Vof pockets conned between two 'adjacent blades in the working chamberWC. Referring to Fig. 3. the pocket E, which is increasing in size, is cut oi from communication with either the pressure chamber 42m or the exhaust chamber, and the air in this pocket is permitted to expand and consequently transform energy to the rotor.

Pressure in the chamber 42a, combined with the mitted through these ports or holes in the cylinder to the inside face of relief valve 41, which forces the valve to the open position illustrated in Fig. 3. Thereafter, the stream .of air exhausting through the relief ports-impinges against the inside face of relief valve 41 to hold the latter open as long as the motor is running in the forward position. As the pocket contracts in size, (see pocket C in Fig. -3), air escaping through the -relief ports 46h as well as through slots 44 reduces or eliminates loss of power that might otherwise result from the piston blades compressing the air in this pocket.

While the invention has been particularly described with reference to a single illustrative embodiment, it will be apparent that many changes and adaptations thereof may be made within the spirit of the invention and within the scope of the appended claims.

What is claimed is:

1. A reversible rotary motor comprising a cylinder, a rotor eccentrically mounted therein to forma working chamber between the rotor and the cylinder, said working .chamber being of maximum width at its center and converging at both sides toward the ends bf the working chamber, blades carried by the rotor and mounted for radial movement in slots formed in the rotor, the outer ends of the, blades being adapted to contact with the .inner circumferential wall of the cylinder,.a pair of fluid openings in the cyl- 'inder symmetrically arranged on opposite sides of the working chamber and communicating with the latter, means adapted to admit live pressure uid to the vopening on one side of the working chamber and connect the opening o n the other side to exhaust and vice versa, whereby the rotor may be driven in opposite directions, a pair of sets of auxiliary exhaust ports, one set being on each side of the working chamber and communicating with. the latter, a valve associated with each set of auxiliary ports and adapted to close the associated set of ports when-the opening on the same side of the .working chamber is conn ected to live pressure fluid, said valve fitting the outside of the cylinder and covering said ports and being held in engagement with the cylinder by live pressure fluid, said valve being free to move in a radial direction out of contact with the cylinder to open said ports when the opening on the same side of the working chamber is connected to exhaust, and means for preventing leakage between the outer edges of the blades and 5 the inner wall or the cylinder, said means comprising passages admitting pressure fluid to the inner edges of the rotor slots to force the blades outwardly, said blades being of greater thickness than the width of any of the auxiliary exhaust ports in a circumferential direction.

2. A rotary reversible fluid pressure motor comprising a casing, a cylinder in said casing, a rotor eccentrically mounted in said cylinder to provide a Working chamber between the rotor and cylinder, said Working chamber being of maximum width at its center and converging at its sides toward the ends of the working chamber, radially movable blades carried by the rotor and projecting into the working chamber, a pair of fluid chambers. between the cylinder and casing, one at each side of the working chamber, one or more openings in the cylinder adapted to maintain said chambers in constant communication with each of the respective ends of the working chamber,

selectively operable means including a throttle valve for simultaneously admitting live pressure uid to one of the uid chambers and exhausting the other fluid chamber and vice versa, Whereby to drive the rotor in opposite directions, means for shortening the effective length of the exhaust side of the working chamber as compared with aova'zae the power side, said means comprising a plurality of relief ports extending through the cylinder, each of said relief ports being atone side of the Working chamber and situated nearer to the center thereof than any of said openings, said relief ports being adapted to communicate with the adjacent fluid chamber when the latter is connected to exhaust, and means for closing said relief ports when the adjacent fluid chamber is connected to live pressure uid, the last-mentioned means comprising a relief valve of segmental cylindrical shape adapted to t the outside of the cylinder and to cover said ports, said relief valve being arranged to move entirely out of engagement with the cylinder in response to pressure in said Working chamber and to be held out of engagement therewith by the impingement of pressure uid discharged through said ports, means for guiding the relief valve in its movement toward and away from the cylinder. said guiding means being supported by the casing, and a spring supported by the casing and contacting with said relief valve to urge the latter toward the cylinder.

. '3. A rotary reversible fluid pressure motor according to claim 2 in which the .guiding means for the relief valve comprises a plurality of radially extending -pins received within apertures in the relief valve, said apertures being out of registry with any of the relief ports.

LESTER A. AMTSBERG. 

